Pneumatic clutch controller with supplemental spring



Dec; 5, 1933. I DE N. MccoLLuM ,938,080

TNEUHATIG CLUTCH CONTROLLER WITH SUPPLEMENTAL SPRTNG ma Feb. 24, 19:52

INVENTOR BY? 2 a ATTORNEY Patented Dec. 5,1933 2 UNITED STATES PNEUMATIC CLUTCH CONTROLLER WITH- SUPPLEMENTAL SPRING Henry J. De McCollum, Long Branch, N. J.

Application February 24, 1932. Serial No. 594,802

11 Claims.

This invention relates to fluid pressure controlled clutch mechanism generally, and is more specifically designed to produce a simple attachment for an automatically operated clutch mechanism on motor cars, which shall produce what is known as the two-stage action in the automatic closing or engaging of such clutch.

In an apparatus of this kind the motive power is usually supplied by a partial vacuum or subatmospheric pressure existing in the intake manifold of the car motor when the motor is running and the carburetor throttle valve is closed, or nearly closed. The pressure differential produced by connecting said intake manifold with a cylinder, bellows or diaphragm or other expansible and contractive unit then acts to pull the clutch open, against opposition of the springs employed.

' 39 H. K. McCollum and myself, Serial No. 509,310,

filed January 17, 1931', to automatically produce a rapid initial closing movement of the clutch parts up to the'point where contact occurs and thereafter a slower closing movement during which the clutch parts are forced into more intimate contact in order to insure the proper degree of friction between them to permit the clutch apparatus to transmit the full power of the motor. An apparatus of the type heretofore employed to for this purpose has usually been somewhat complicated and, as there are situations in which the less accurateacontrol and adjustment of this twostage apparatus is suflicient, I have developed the simple arrangement for this purpose here illustrated, in which the action of the clutch closing springs is supplemented by the action of a second spring which is eifective during the initial portion of the clutch closing movement but automatically ceases this effective action after, or about the time, the lost motion in the clutch parts has been taken up and the clutch surfaces have been brought into their initial contact.

The-best form of apparatus at present known to me embodying my present invention is illustrated in the accompanying figure of drawing,

which is a diagrammatic illustration of parts of the motor car with the automatic clutch apparatus operatively attached thereto, parts being shown in section and others broken away or omitted.-

In the drawing the portions of the apparatus there shown, which heretofore have been in use, include the clutch pedal 1 fast on the clutch operating rotatable shaft 2 and tension spring 3 normally tending to swing said clutch pedal in a cIockwise direction, thus representing diagrammatically the usual clutch closing springs; 4 is a portion of the foot board of the motor car; 5 is a portion of theintake manifold of the motor; 6 is the carburetor and 7 the smaller pedal or plunger by which both the carburetor throttle and the valve 10 are successively operated. 8 is the usual cylinder open at the right end and connected at its other, closed end by the conduit 9 with the intake manifold 5, this conduit being :5 controlled by valve 10 which, when moved to the left, shuts off connection between the two sections of the conduit 9 and opens the right hand portion of the conduit 9 to the atmosphere through a valve port, the effective area of opening of 30 which is of course fixed, and may be further adjusted to the predetermined extent by manipulation of the valve 10. A piston 12 slides in cylinder 8 and is rigidly connected to a piston rod 13 which has its free end pivotally connected at 14 35 to the clutch pedal 1; the cylinder 8 has a hinged mounting on some fixed portion of the motor car structure as indicated at 15. The usual spring 19 tends to force the small pedal '7 to the right, and 18 represents generally a system of linkage g connecting this pedal with the valve 10 and with the carburetor throttle valve.

The mode of operation of the above described apparatus is well known, the valve 10 automatically opening the connection from the intake 5 manifold to cylinder 8 when the pedal 7 is fully retracted by the spring 19; with the result that the pressure differential on the piston 12 then pulls the clutch open against the resistance of the clutch springs. When, however, pedal '7 is moved to the left the connection to the intake manifold is closed and the right hand portionof conduit 9 is thereafter gradually opened to the atmosphere, -thus permitting air to rush in and permit the clutch springs to pull piston 12 to the right, gradually closing the clutch.

To this apparatus, according to my present invention,'is added a second spring 16, which may be placed in the cylinder 8, as shown, behind piston 12 so it will be compressed during the lat- 1m ter portion of the motion of said piston toward the left in opening clutch. This spring may be so designed that it will not expand beyond the extent indicated in the drawing, or it may be so designed as to have a further range of expansion when free but have a flexible link 17 connected to its extremities, or to its anchorage, so that it cannot expand beyond a predetermined extent.

The operation of the so modified apparatus will evidently result in a very rapid initial movement of the clutch lever 1 to the right in the direction producing the initialclutch engagement, at which point (if the parts are properly proportioned) the spring 16 will cease to act and the remaining portion of the clutch closing movement of lever 1 and shaft 2 will take place by reason of the much lesser pull or thrust of the clutch spring 3 then exerted so that any shock of clutch engagement or grabbing action of the clutch may be entirely avoided or at least reduced to a negligible amount.

The movement of the piston 12 during *the above described operation is evidently restrained to a uniform extent which is a function of the rate of inflow of air from the atmosphere through the right hand port of the valve 10, which has then been opened to a certain extent. The combined action of the two sets of springs 3 and 16 will obviously draw this air in rapidly during the initial movement of the piston to the right, but'the single spring 3 can draw it in only much less rapidly after the spring 16 ceases to act. It will be seen, also, that the severe compression of the supplemental spring 16 occurring when the clutch disengaging movement is completed and the piston is near the closed end of the cylinder, and which high compression results in the rapid expansion of such spring when the initiation of the clutch engaging movement of variable, two-stage type of clutch engaging in in elemental physics that the frictional resistance to sliding motion of one surface over another is greatest when such movement is being initiated, much exceeding that occurring after the parts are in movement, and this is especially true when one of the elements so in contact is of relatively soft material such as usually employed for piston packing.

The clutch springs proper used in commercial clutch apparatus and conventionally represented at 3 in the drawing, are of standard strength just sufficient to hold the clutch in engagement, as any excess strength in such springs beyond thatrequirement both adds to the work necessarily expended by the driver in opening the ency to grabbing by the clutch when being closed. When, therefore, a pneumatic clutchactuating servo-motor of the general type here shown and now in general use, is installed on a car already equipped with a standard clutch unit, the extra work then demanded from the clutch springs to overcome the friction of the piston in its cylinder, and of the connecting mechanism, may be more than such springs'can efiectively and promptly supply. As a result the clutch engagement will then be delayed with consequent possibility of the engine racing as the throttle begins to open before the clutch is engaged' to a suflicient degree, or the clutch may slip badly and burn out. The addition of the supplemental spring 18, employed in my invention (as above explained) supplies this particular demand for additional piston moving force, and acts most powerfully at the particular instant when the maximum force is needed to start the piston into motion from its position of temporary rest.

Obviously the second spring 16 may be placed in other positions than that shown and still perform the function above described, but such rearrangement of the apparatus would still operate upon the underlying principle of the present invention and produce the same result, and be within the scope of some of the appended claims.

Having described my invention, I claim:

1. In a fluid pressure actuated device for automatically controlling the movements of the clutch lever of a motor car which is normally pressed towards the clutch closing position by springs, which said device comprises an expansible unit cperatively connected to such clutch lever and means for admitting fluid to the interior of said expansible unit through an orifice of predetermined cross section, whereby such clutch lever is allowed to swing towards clutch closing position under spring pressure as said fluid permits said unit to expand; the combination, with said above described apparatus, of a second spring cooperating with said first mentioned spring means but adapted to act during the first portion only of said clutch closing movement of said lever; whereby rapid movement of said lever up to the position of the initial clutch engagement is caused by the combined action of said springs, but thereafter only a slower movement occurs during which the completion of such clutch engagement under sole action of said first mentioned spring means is effected.

2. A combination such as defined in claim 1, in which said expansible unit comprises a cylinder and piston movable therein and connected to said lever, and in which said second spring is located in said cylinder behind said piston and is capable of expanding only to an extent corresponding to a fraction of the travel of said piston during the clutch closing movement.

3. An apparatus such as defined in claim 1 combined with positive stop means limiting the expansion of said spring.

4. An apparatus such as defined in claim 1 combined with positive means limiting the expansion of said second spring comprising a flexible non-extensible link, one end of which is connected to the spring anchorage while its other end is connected to the free end of said spring.

.5. An automotive vehicle provided with a spring-actuated clutch controlling member, combined with power-operated mechanism cooperating with said member for putting it in positions which will render the clutch either inoperative or operative, said mechanism including means,

distinct from but supplementing the action of the spring of such clutch controlling member, for efiecting a predetermined mode of movement of said member during a predetermined portion of the clutch engaging movement thereof.

6. An automotive vehicle provided with a clutch controlling member= combined with means for moving said member into clutch-closing position and comprising power mechanism for effecting a clutch disengaging movement of said member,

said mechanism comprising means distinct from but supplementing the action of the beforementioned clutch closing means, and positively moving said member toward the clutch-closing position during a predetermined portion of such movement.

7. In an automotive vehicle provided with 'a clutch-controlling member and a means for forcing it into clutch-closing position, a pneumatically actuated clutch-operating motor combined with means for con-trolling the operation of said motor and said clutch-controlling member so as to alternately disengage the clutch or to permit an engagement of the same, and means, supplementing the positive effect of such clutch-closing means, and cooperating with said clutch-operating motor, for determining the mode of movement of said clutch-controlling member during a predetermined portion of the clutch-closing movement thereof.

8. An automotive vehicle provided with a clutch-controlling member and means capable of storing potential energy for effecting the clutchclosing movement of said member, combined with power-mechanism for controlling the operation of said member, said power-mechanism comprising means supplementing the action of said first-mentioned means and capable of increasing the available potential energy for efiecting an engagement of the clutch, said supplementing means functioning to aid in the engagement of the clutch during a predetermined portion of the .clutch engaging throw of said clutch-controlling member.

9. In an automotive vehicle provided with a 8G clutch-controlling member, the combination of a vacuum-operated motor for effecting an oper-.- ation of said member and valve means for controlling the operation of said motor, said motor comprising yieldable means, cooperating with the pneumatic efiect of said motor, for predetermining the mode of movement of said clutchcontrolling element during a portion of its clutch-engaging throw.

10. In a pneumatic clutch-actuating apparatus for motor cars having a swinging clutchcontrolling lever and spring means for moving esaid lever toward clutch closing position, which said apparatus comprises a cylinder closed at one end and containing a piston operatively connected to said lever, together with means for exhausting air from the closed end of said cylinder so as to draw said piston toward such closed end and thereby produce a clutch opening movement of said clutch lever against the opposition of said spring means, the combination, with said above recited apparatus, of a supplee mental spring remote from such clutch and lever, but adapted to supplement the clutch closing action of said first mentioned spring means during 105 the first portion only of said action, thereby assisting the latter to overcome the frictional resistance of said piston while being started from its positionof rest to initiate the clutch closing movements of said apparatus.

11. A combination such as defined in claim 10 in which said supplemental spring is located in the closed end of said cylinder and confined between the cylinder head and said piston.

' HENRY J. DE N. McCOLLUM. 115 

